EXTRACELLULAR DNA FROM SERPULINA-HYODYSENTERIAE CONSISTS OF 6.5-KBP RANDOM FRAGMENTS OF CHROMOSOMAL DNA

Preparations of chromosomal DNA from a number of Serpulina hyodysenter iae strains have shown, using agarose gel electrophoresis, the presenc e of an additional band with a mobility similar to that of a 6.5 kbp l inear DNA fragment. Analysis showed that this is not a plasmid but rat her a form of extracellular DNA like that observed for Gram-negative b acteria. However, unlike the extracellular DNA from Gram-negative bact eria, which showed a similar band profile to that of the DNA from whol e cells, that from S. hyodysenteriae consisted primarily of fragments of a fixed 6.5 kbp.